ROBOTIC TRANS-ABDOMINAL PREPERITONEAL APPROACH (TAPP) APPROACH FOR LATERAL INCISIONAL HERNIAS

ABSTRACT 
Background:
 Lateral incisional hernias arise between the linea alba and the posterior paraspinal muscles. Anatomical boundaries contain various topographic variations, such as multiple nearby bony structures and paucity of aponeurotic tissue that make it particularly challenging to repair. 
Aim:
 To describe a robotic assisted surgical technique for incisional lumbar hernia repair. 
Methods:
 Retrospective data was collected from four patients who underwent robotic-assisted repair of their lumbar hernias after open nephrectomies. 
Results: Age ranged from 41-53 y. Two patients had right sided flank hernias while the other two on the left. One patient had a recurrent hernia on the left side. The patients were placed in lateral decubitus position contralateral to the hernia defect side. A trans-abdominal preperitoneal approach was used in all cases. Each case was accomplished with two 8 mm robotic ports, a 12 mm periumbilical port, and a 5 mm assistance port that allowed docking on the ipsilateral hernia side. The hernias were identified, a preperitoneal plane was created, and the hernia sac completely dissected allowing for complete visualization of the defect. All defects were primarily closed. Polypropylene or ProGripTM mesh was applied with at least 5 cm overlap and secured using either #0 Vicryl® transfacial sutures, Evicel® or a combination of both. The peritoneal space was closed with running suture and the ports were removed and closed. The average surgical length was 4 hr. The post-operative length of stay ranged from 0-2 days. 
Conclusion:
 The robotics platform may provide unique advantages in the repair of lateral incisional hernias and represents a safe, feasible and effective minimally invasive approach for the correction of lateral incisional hernias.

Trocar positioning A 5 mm Optiview port was inserted through the ipsilateral subcostal area. One peri-umbilical 12 mm port and two 8 mm ipsilateral paramedian ports were placed and the robot was docked from the ipsilateral hernia side. The 4 th arm was used for retraction and some bed assist help (Figure 1).

Locating the defects and creating the pre-peritoneal plane
The abdomen was explored until the lumbar herniating defects were encountered. Adhesiolysis and complete reduction of the hernia contents was performed as necessary. A peritoneal incision was made at least 5 cm medial to the edge of the defect ( Figure 2A) and a large pre-peritoneal plane was created. (Figures 2B and C) Dissection of the hernia sacs and defect closure The hernia sacs were completely dissected and reduced allowing for complete visualization of the hernia defect ( Figure  2D). The respective defect sizes were 11x10 cm, 11x16 cm, 4x5 cm with a neighboring 1.5x2 cm defect, and 9x8 cm. The mean defect area was 99 cm 2 . All defects were primarily closed with V-Loc TM (Medtronic MN, USA) sutures ( Figures  3A, B, C). In the two cases with defects of over 9 cm, barbed sutures were used with progressive tensioning of the suture. Furthermore, reduction of pneumoperitoneum to 10 mm Hg was used to achieve an adequate tension closure of the hernia defects. On one occasion, a Progrip mesh was placed overlying the primary repair to reduce tension on the suture line. The large defect was closed under high tension and it was in close proximity to the ribs and anterior superior iliac spine. The concept was to use the large gripping surface of the mesh to reduce central tension on the closure followed by a bigger mesh to create an adequate overlap of the repair.
Positioning and fixation of the mesh Next, the preperitoneal space was measured ( Figure 3D) and either Polypropyelene or ProGrip TM mesh was trimmed to allow for at least 5 cm of overlap in all directions. The meshes were secured using either #2-0 Vicryl ® sutures, Evicel ® or a combination of both ( Figures 4A, B). Transfacial sutures (two 0 Vicryl ® ties with a suture passer) were used in one case (11x16 cm defect), which helped with positioning and fixation of the mesh.
The peritoneal space was closed with running #2-0/3-0 Vicryl ® /VLock and no residual defects were noted in the peritoneum ( Figure 4C). The ports were removed, and the robot was undocked at this time. Average procedure length was 4 hr ( Table 2).

INTRODUCTION
L ateral incisional hernias (LIH) arise between the linea alba and the posterior paraspinal muscles, between the iliac crest and the costal margin 5 . These anatomical boundaries contain various topographic variations, such as multiple nearby bony structures and paucity of aponeurotic tissue, that make LIH particularly challenging to repair. These constrains can make it difficult to achieve a wide overlap of mesh, prevent primary closure of defects, and provide adequate mesh fixation 4,5 . The European Hernia Society has proposed a classification for lateral incisional hernias according to their position (subcostal, flank, iliac, lumbar), recurrence, length and width 2 .
Most technical reports in the literature have focused on open approaches for the repair of LIH with varying degrees of success 11,12,13 . There is a paucity of data regarding minimally invasive techniques for the repair of this challenging surgical entity 3,6,7,8,9,13,15,16 . In fact, there are very few reports in the literature that focus on robotic repairs for LIH 1,5,17 Furthermore, they contain a very limited number of patients with limited post-operative follow-up.
We aim to outline an emerging, robotic-assisted, lateral incisional hernia repair technique and to report on the outcomes.

METHOD
This study was approved by the institutional ethic committee under number IRB # 2020-11160. It is a retrospective analysis of four patients who underwent robotic transabdominal preperitoneal approach (TAPP) repair of their lateral incisional hernias after open nephrectomies.

Technique
The patients were a 53 year-old male patient with an incisional hernia in the right flank, a 41 year-old male with a recurrent left sided incisional hernia, a 77 year-old female with an incisional hernia on the left flank, and a 62 year-old male with a right flank incisional hernia ( Table 1). All patients were operated with the Da Vinci Si robot system (Intuitive Surgical).
Positioning of the patient and establishing pneumoperitoneum TAPP was used in all cases. The patients were placed in lateral decubitus position contralateral to the hernia defect side ( Figure 1). The abdominal cavity was insufflated via a Veress needle to 15 mm Hg.

RESULTS
Post-operative length of stay ranged from 0-2 days. One of the patients was readmitted on the 2 nd post-operative day with a clinically symptomatic seroma and managed conservatively with pain control and observation. At 90 days, none of the patients developed recurrence or bulging at the surgical site and all had complete return to full physical activity (Table 3).

DISCUSSION
Introduction to the problem LIH remain a rare but challenging problem to most general surgeons. The unfamiliar anatomy, the constraints of the lateral abdominal wall, and the lack of an established surgical technique makes this surgical entity particularly difficult to treat 5 . As a result, there is a paucity of literature discussing repair techniques, the optimal surgical modality, and the outcomes after repair. This is especially true in minimally invasive approaches to LIH repairs 7-15 .

Our conclusions and tips
In our report, we highlight four cases of successful treatment of LIH using a robotic-assisted approach. All patients had an incisional hernia from previous open nephrectomy and underwent successful TAPP repair of LIH. Laterality was equally distributed with a 3:1 predominance of male to female subjects. Mean age was 58 years old, all patients had an elevated BMI with a mean of 28.5. There were no conversions to open procedure. The average defect size was 76 cm 2 with an average mesh size of 408 cm 2 . One patient was readmitted to the hospital with a symptomatic seroma that was successfully treated with supportive management.
Appropriate patient selection and preoperative planning remains a crucial part of the evaluation of patients presenting with LIH. A key component remains preoperative computerized tomography imaging of the abdominal wall to evaluate the defect size, contents, the presence of previous mesh, and the relative laxity of the lateral abdominal. Patients presenting with large defects resulting in a weak lateral abdominal wall should be counseled the possibility of having some laxity in the abdominal contour postoperatively. Similarly, those presenting with a lateral abdominal bulge, which is normally seen from denervation of the lateral muscles from previous incision rather than a true hernia, should be counseled on the possibility of similar outcomes. In these cases, the robotic platform may offer better visualization, improved intracorporeal suturing, a more extensive extraperitoneal dissection and the ability to use a large mesh in order to minimize such abnormalities in the contour of the abdominal wall.
One of the critical steps to the procedure is creating an adequate extraperitoneal plane in order to properly seat the mesh with adequate coverage. Prior to this, all efforts should be made to reduce all hernia contents back into the abdomen. An appropriate peritoneal flap starts at about 5 cm from the edge of the defect and extends a minimum of 5 cm in all directions relative to the defect. Keep in mind that as you near the semilunar line, the peritoneum gets thinner and one should take extra care to select the appropriate plane when starting the dissection near this landmark. The same caution should be observed when dissecting close to the ribs and under the diaphragm, where there is less fat between peritoneum and muscle layers. When nearing the hernia sac, efforts should be made to dissect and reduce the sac in order to reveal the true hernia defect.
Primary closure of the defect should be attempted and best done with a V-Loc TM suture allowing the surgeon to bring two fascial edges together by gradually and equally spreading the tension along the entire edge, rather than focusing the tension at the crotch of the suture. When possible, use more than one V-Loc TM along the wound to minimize high tension areas. For larger defects, relaxing maneuvers, such as decreasing the flex position of the patient at the table, which reduces the distance between the ribs and anterior superior iliac spine, and decreasing the pneumoperitoneum can be used to facilitate defect closure.
The choice of mesh remains controversial. We used two polypropelene and two ProGrip TM meshes with adequate results. The ProGrip TM offered the extra advantage of reducing tension along the closed hernia defect. Medium and heavy weight polypropelene offer excellent tensile strength at a minimal cost. The mesh is usually anchored to the anterior abdominal wall using vicryl sutures or evicel. Special care should be taken to avoid sutures far posteriorly, since the lumbar plexus and its branches originate in the intimacy of the psoas muscle. Thus, one should especially avoid traumatic fixation to this area.
Finally, appropriate peritoneal coverage remains a key concept of this repair that requires special attention. Holes in peritoneal coverage should be closed with absorbable sutures to prevent adhesions to intra-abdominal structures. In large peritoneal flap defects that are not amenable to simple closure; alternatives include omental flaps (when available), use of redundant hernia sac, the use of barrier methods such as oxidated cellulose (Surgicel TM ), or even using coated or absorbable meshes to avoid direct contact between the extraperitoneal mesh and intra-abdominal structures. Adequate overlap, with a full closure or the peritoneum will allow the peritoneal sac to maintain tension of the mesh and avoids dislodgment.
Overall, the TAPP approach avoids a posterior component separation procedure as is required with the extended view total extraperitoneal approach (eTEP). TAPP approach preserves the retromuscular muscle for future repairs, should they become necessary. The reduced cost in disposables, such as coated meshes or tackers, may off load some of the increased cost of using the robotic platform. However, if a patient presents with a defect that is less than 5 cm from the midline or if there is an associated midline defect, an eTEP approach should be strongly considered.
We are continuing to push the limits of minimally invasive hernia surgery. Laparoscopy remains an acceptable, cost-effective, and widely available modality for the repair of many types of hernias, but it does have specific limitations. This is especially true of surgical procedures with tight working spaces that require enhanced dexterity and visualization, much like is required for minimally invasive LIH repairs. The enhanced 3D visualization of the robot, the dexterity and freedom of mobility of the instruments, and the extra robotic hand decrease may overcome the technical difficulties that can be seen with laparoscopy. As early adopters, we expect the robotic platform to become the standard of care for minimally invasive repairs of LIH.
OriginAl ArTicle -Technique

4/5
Additional studies are needed to evaluate the relative safety, learning curve, costs, optimal technique, and long-term outcomes of minimally invasive LIH repairs.

CONCLUSION
In our early experience is evidence that the robotic platform may offer a feasible, lasting, and safe minimally invasive approach to the repair of these notoriously difficult hernias.